Adds a unit test for Cargo Crates to prevent infinite credit oversights. (#89023)

## About The Pull Request

I was kinda shocked that we didn't have something for this considering
that it's an unspoken rule of cargo to check that a crate does not sell
back for more than it's price and that the one comment saying to do so
has been doing some heavy lifting for the last 12 years.

I'm a novice when it comes to unit testing specifically so hopefully the
smoothing out that needs to be done should be fairly quick.

*Edit (2/22/25):*
The following changes were also made in order to allow for this unit
test to work smoothly:

Exports now have a market define added to them, as the purpose of this
unit test is to test exports that occur on the station, bought from
supply and then sold back to supply. As such, these market defines
exclude exports specific to pirates (since the cargo shuttle cannot sell
living mobs back, preventing you from making 10k per parrot crate.).

I've also added the `abstract` variable to some export datums, to
signify that a given export is either variable, or not meant to be
compared against the value of it's own container, such as with gas
canister's base export value as their export datums are generated
dynamically. (The subtypes are not abstract, however.)

The verb, `/mob/living/verb/tally_physical_credits()` has been changed
to `/mob/living/proc/tally_physical_credits()`, because that's my B and
does effect some economy back end but it's a one line fix so I just
absent-mindedly fixed it here instead of atomizing it out. I can
one-line it otherwise.

Mulebots now no longer runtime on spawn as they set their own to their
own `get_turf` as opposed to pulling their `loc`.

A few supply packs have had their prices bumped up slightly to actually
pass the test itself:

* `/datum/supply_pack/misc/candles_bulk`
* `/datum/supply_pack/security/armor`
* `/datum/supply_pack/security/helmets`
* `/datum/supply_pack/security/baton`

## Why It's Good For The Game

Prevents future infinite credit bugs that could have been missed by
simply checking the sale value in game.

## Changelog

🆑
fix: To prevent infinite sales issues, security helmets, armors, and
batons packs now all cost 600 credits, up from 400.
fix: Candle packs now cost 400 credits, up from 300, and candles now
sell for 12.25 cr each.
/🆑

---------

Co-authored-by: LemonInTheDark <58055496+LemonInTheDark@users.noreply.github.com>

code/__DEFINES/cargo.dm

@@ -13,6 +13,9 @@
 
 #define SUPPLYPOD_X_OFFSET -16
 
+///DO NOT GO ANY LOWER THAN X1.4 the "CARGO_CRATE_VALUE" value if using regular crates, or infinite profit will be possible! This is also unit tested against.
+#define CARGO_MINIMUM_COST CARGO_CRATE_VALUE * 1.4
+
 /// The baseline unit for cargo crates. Adjusting this will change the cost of all in-game shuttles, crate export values, bounty rewards, and all supply pack import values, as they use this as their unit of measurement.
 #define CARGO_CRATE_VALUE 200
 
@@ -29,6 +32,12 @@
 /// Universal Scanner mode for using the price tagger.
 #define SCAN_PRICE_TAG 3
 
+// Defines for use with `export_item_and_contents()`, aka the export code that sells the items.
+/// Default export define, these are things that are sold to centcom.
+#define EXPORT_MARKET_STATION "supply"
+/// Export market for pirates.
+#define EXPORT_MARKET_PIRACY "piracy"
+
 ///Used by coupons to define that they're cursed
 #define COUPON_OMEN "omen"